1. Field of the Invention
This invention relates generally to the manufacture of electronic components, and more particularly to using a structure which is substantially perpendicular to a first plane of a target platform to implement passive electronic components.
2. Related Art
Semiconductor components are often manufactured using a ball grid array (“BGA”) package, where metallic solder balls composing tin, silver and copper, are pre-soldered at pad contacts of a component package for soldering the semiconductor component to a target platform, such as a printed circuit board (“PCB”). Semiconductor components are also often manufactured in a leadless grid array (“LGA”) package where there are no solder balls at the pad contacts of the package. Instead, a thin layer of solder paste is printed on the metal contacts of a PCB during product assembly to solder the semiconductor component on the PCB.
Other packages are also used in semiconductor component manufacturing. For example, a quad flat-pack package (“QFP”) or a small outline integrated circuits package (“SOIC”) uses gull-wing shaped metal leads attached to the periphery of the package to couple the packaged semiconductor component to a PCB. As another example, a dual-in-line package (“DIP”) or a pin grid array package (“PGA”) sticks metal pins at the periphery of the package or at the bottom surface of the package for inserting the packaged part into a socket or for soldering it into a set of through-holes on a target platform, such as a PCB. Additionally, a ceramic-leaded chip carrier (“CLCC”) package or a plastic-leaded chip carrier (“PLCC”) package affixes J-shaped metal leads to the periphery of a packaged semiconductor component for connecting the semiconductor component to a target platform, such as a PCB.
One thing common to many conventional packages for semiconductor component is that nothing more than metal contacts, metal pins, or solder balls are attached to pad contacts of the packages to connect the semiconductor component to a target platform.
When using a semiconductor component, such as an integrated circuit (“IC”), passive components, also referred to as “passives,” such as resistors, capacitors or inductors, are often added to make the semiconductor component function properly. For example, decoupling capacitors are often connected to the power pins of an IC component to filter out power noises. A current limiting resistor is often coupled to a driver pin of an IC component to limit driver output current. Or, a termination resistor is often coupled to a signal path to suppress reflection in the high speed trace. Conventionally, these passives are often placed near the pins of the IC component to which the passive is coupled in order to maximize their effectiveness. However, these passives are placed beyond the IC package outline, which often occupy substantial area on the target platform and also compete with interconnect layout routing around the IC component, especially if the IC package has high pin-count.
FIG. 1 illustrates a simplified version of a conventional printed circuit board (“PCB”) assembly, where a conventional, horizontally structured passive component 120 and an IC component 130 are soldered to a PCB 100. The IC component 130 includes a set of IC pads 135 which are soldered to a set of target contacts 115 on PCB 100. Solder balls connect the IC pad 135 and the target contact 115 on the PCB. To connect a passive component 120 to a pad of IC component 130 on the PCB 100, two target contacts 111 and 112 are added to the surface of PCB 100, where the electrodes 121, 122 of the passive component 120 are connected to the target contacts 111, 112. To connect the electrode 122 of the passive component 120 to an IC pad 135 in the IC component 130, an additional PCB trace 114 is added to the surface of PCB 100, which connects target contact 112 to a corresponding target contact 115 in IC component 130. In the example depicted by FIG. 1, the passive component 120 occupies PCB area, and may also block signal traces around the IC component 130 on the PCB 100.
There is an additional potential problem in using the conventional passive components. For mobile or high density electronic products, there is a continuous trend to miniaturize the package size, including the supporting passives. For example, the common size of passive components used in a high density DRAM module design has been changed from a 0603 package having a dimension of 60 mils in length and 30 mils in width to a smaller 0402 package having a dimension of 40 mils long by 20 mils wide. In mobile devices, such as cellular phone, a 0201 package of 20 mils long by 10 mils wide which further reduces the size of area occupied by the passive components becomes more widely used. The current state-of-the-art for passive component is a 1005 package having a dimension of 10 mils in length and 5 mils in width. This reduced passive size makes it difficult to solder conventional passive components to a target platform, such as a PCB, because of the increased likelihood of insufficient soldering or solder bridging problems. Much of the difficulties in soldering smaller passives to a target platform originate from the horizontal structure in which most passives are fabricated, with an electrode at each end of the horizontal structure. A solution that can reduce the target platform area overhead used by the passive component and while reducing the bridging and/or insufficient soldering problem encountered by the ultra-small passives during PCB assembly is useful.